1. Technical Field
The present disclosure relates to detection of underground lines and, in particular, to signal processing for cable location equipment.
2. Discussion of Related Art
Underground pipe and cable locators (often termed line locators) have existed for many years and are described in many issued patents and other publications. Line locator systems typically include a mobile receiver and a transmitter. The transmitter is coupled to a target conductor, either by direct electrical connection or through induction, to provide a current signal on the target conductor. The receiver detects and processes signals resulting from the electromagnetic field generated at the target conductor as a result of the current signal, which can be a continuous wave sinusoidal signal provided to the target conductor by the transmitter.
The transmitter is often physically separate from the receiver, with a typical separation distance of several meters or in some cases up to many kilometers. The transmitter couples the current signal, whose frequency can be user chosen from a selectable set of frequencies, to the target conductor. The frequency of the current signal applied to the target conductor can be referred to as the active locate frequency.
In some cases, for example in power lines, the target conductor may carry a current signal without the need for an outside transmitter. In either case, the target conductor then generates an electromagnetic field at the active locate frequency in response to the current signal.
Therefore, there is a need to better process the electromagnetic signals received at the receiver.